Technical Field
The exemplary and non-limiting embodiments relate generally to a robot and, more particularly, to a joint between a wrist of a robot and an end effector.
Brief Description of Prior Developments
Vacuum robots are used in manufacture of semiconductor, flat panel and LED as well as other markets and applications. Load and capacity of payloads have increased for these robots over the years. Thus, demands on an arm of these robots, in terms of deflection, stiffness and weight, have increased over the years. By way of example, if the deflection of the arm is large, there must be additional height in valves, clearances in chambers and Z-direction stroke in the robot. This results in increased costs to manufacture the robots. One approach to increasing stiffness is by selecting higher stiffness materials to minimize deflection. By way of example, an aluminum arm may be made out of stainless steel. Here, the deflection is reduced, but the weight and cost of the arm are both increased resulting in the need for a higher torque producing robot drive to maintain the same motion profiles. This would increase costs. Accordingly, there is a desire to produce arms that have minimum deflection and weight to not need the added costs.
Another problem arises due to the temperature of the payload. A robot arm may deform due to thermal expansion. If the arm deforms in an unpredictable or non-uniform manner, there must be additional height in valves, clearances in chambers and Z-direction stroke in the robot. This would result in additional costs. Accordingly, there is a desire to produce arms that deforms, due to thermal effects, and expands and contracts in a uniform manner to not need the added costs.